Numerous industries utilize hydrazine on a daily basis. Highly toxic hydrazine fuels, for example, are respectively utilized by the United States Air Force and NASA as an emergency power source on the F-16 and as rocket propellant. The civilian industry also requires hydrazine in the manufacture of agricultural chemicals and pharmaceuticals, in photography, and also, for example, as an oxygen scavenger to prevent corrosion in boilers. Additionally, large volumes of such chemicals are shipped across the highways and rail systems annually, increasing the probability of an accidental spill.
An inadvertent release of hydrazine to the environment can be extremely hazardous due to the mutagenic nature of such chemicals, which can induce tumor growth in human beings years following even a low-level exposure. Hydrazine compounds are classified as suspected human carcinogens and the permissible levels of exposure have been reduced to 10 parts per billion (ppb) over an eight-hour workday. A hydrazine spill remediation process, to be developed, should not only remediate the hydrazine, but also should not generate other hazardous materials. An in-situ processing method involving direct application of the treatment reagent or process to the spill is preferred.
An accident involving a transport trailer, for example, may spill four to five thousand gallons of hydrazine, whereas a catastrophic failure of a fuel storage vessel at a launch facility may release twenty thousand gallons or more of the propellant. For example, a rail car derailment resulting in a release of hydrazine occurred in Southern Calif. on Jul. 28, 1991.
Hydrazine and hydrazine derivatives are readily combustible reducing agents that react violently with oxidizing agents and thus present a serious safety hazard. Hydrazine and hydrazine derivatives are well known components of liquid rocket fuels in conjunction with an oxidizing agent such as dinitrogen tetroxide. Thus, at facilities where liquid-fueled rockets are prepared for flight, there is a particular need to provide reliable and sensitive methods and systems for decontaminating objects such as fighter jets and maintenance equipment thereof, and exposed environments which can become contaminated with hydrazine. Ideally, such hydrazine remediation methods and systems should also have a limited, if negligible, effect on the environment.
Examples of hydrazine neutralization techniques are known. One example of such a technique is disclosed in U.S. Pat. No. 4,804,527, entitled “Method and Composition for Safely Decomposing Hydrazine,” which issued to Tatarchuk, at al. on Feb. 14, 1989. As described in U.S. Pat. No. 4,804,527, hydrazine can be safely rendered harmless by contacting it with a composition comprising cupric oxide on a porous support. Neutralization can be achieved by drawing the hydrazine into the pellet pores where a reduction reaction of cupric oxide takes place. The critical consideration is to avoid flashing or spontaneous thermal decomposition of the hydrazine, Heat of reaction is quenched by the heat capacity of the pellet and water dilution.
The conversion of hydrazine group compounds to stable organic compounds as a result of a reaction with a dicarbonyl-compound like ketoglutaric acid is described in the U.S. Patent Application Publication No. 2004/0024251 by Helvenston, et al. entitled “Methods and Systems for Hydrazine Remediation”. In U.S. Patent Application Publication No. 2004/0024251, which is incorporated herein by reference, the conversion assists in the remediation of the hydrazine group compound from the object. The stable organic compound produced as a result of the reaction between the dicarbonyl-compound and hydrazine group compound can then be treated with a metal catalyst and hydrogen to produce glutamine or a derivative thereof. The compound then becomes yet another non-hazardous material. Such an approach is also described in U.S. Pat. No. 7,074,959, which issued to Helvenston, et al. on Jul. 11, 2006 and which is also incorporated herein by reference in its entirety.
The present invention is a novel application of the reaction between hydrazine and a dicarbonyl compound for remediating hydrazine from a hydrazine-contaminated gas.